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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit organization. That differs sharply with laboratory estimates, which suggested a 75% reduction in pollution.

Researchers examined information from onboard energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a senior analyst involved in the study. “That gap is widening and creates a significant problem. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to total distance. The team determined that only 27% of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official estimates. That occurred because EV motors were insufficiently powerful enough to function alone, resulting to engines using fossil fuels for almost a third of the distance completed in EV mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several large carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running expenses than would be estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy debates as carmakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with significant automotive industries.

Several high-level politicians have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One external energy economics expert, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which segments of the automotive sector claimed there was insufficient information to properly assess actual CO2 output.

“The results show, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert said. “Any regulatory adjustments concerning PHEVs should be made with extreme care and in the light of this data.”